1. Technical Field
This disclosure relates generally to an inkjet carriage unit and an image forming apparatus, such as an inkjet recording apparatus, using the same.
2. Description of the Related Art
Image forming apparatuses such as inkjet recording apparatuses have a scanning part that causes a carriage having recording heads mounted thereon to scan paper in a predetermined scanning direction while guiding the carriage with a guide rod. The recording heads are driven based on image data during scanning by the carriage so that an image is formed. In general, these inkjet recording apparatuses include a linear scale bearing marks for detecting the position of printing heads, and a read sensor to read the marks while moving along the linear scale. The linear scale is shaped like an elongated film extending in the scanning direction of the carriage. Its marks are provided at very narrow intervals (for example, 0.084 mm in the case of 300 dpi) (see, for example, Japanese Patent No. 2958131).
In image forming apparatuses such as inkjet recording apparatuses as described above, various modifications such as making many component parts and members replaceable are made so as to make apparatus service life much longer, for example, tenfold. In this respect, there is a need to remove and replace a carriage or replace a light emission part and a light reception part forming an encoder sensor. This is because longer apparatus service life may cause contamination of the encoder sensor, specifically, its light emission part and light reception part, with ink mist, thus causing a problem in that position detection cannot be performed with accuracy.
In order to perform such replacement, first, it is necessary to remove the carriage from a guide rod. In this case, the conventional structure also requires the linear scale to be removed. However, since the marks of the linear scale are arranged at very fine intervals, an operator is prevented from touching the marks with her/his hand. This is because the sebum of the hand adheres to the marks of the linear scale through touching them so as to prevent the marks from being read. Therefore, according to the conventional structure, it is almost impossible to actually remove and replace the carriage.